Electromagnetic shielding apparatus



April 21, 1953 T. E. HANLEY ELECTROMAGNETIC SHIELDING APPARATUS Filed Sept. 17, 1945 THURE E. HANLEY My;

Patented Apr. 21, 1953 ELECTROMAGNETIC SHIELDING APPARATUS Thure E. Hanley, Washington, D. 0. Application September 17, 1945, Serial No. 616,939

4 Claims. (01. 250-33) (Granted under Title 35, U. S. Code (1952),

see. 266) This invention relates to electrical shielding.

An object of the invention is to provide novel electrical shielding means.

Another object of the invention is to provide novel means reducing the mutual coupling between two antennas.

A further object of the invention is to provide novel means reducing the mutual coupling between two antennas and adapted to occupy a minimum amount of space.

In accordance with the invention, there is provided shielding means comprising one or more vanes which, in a preferred embodiment, circumscribe the convex surface of a cylindrical element.

A more complete understanding of the invention may be had by reference to the following description and to the accompanying drawings in which:

Fig. 1 is a side view, one-half sectional, of an embodiment of the invention, and

Fig. 2 is a top view of the embodiment shown in Fig. 1.

Referring now to Figs. 1 and 2, there are shown two antennas 10, II which are separated in space by arelatively short distance, of the order of two to five wavelengths. The embodiment of the invention shown in the drawings provides means for reducing the magnitude of the mutual coupling comprising a cylindrical element 12 made of conductive material and placed between antennas ill, I I. A plurality of conductive vanes 13, i4, l5, 16, are provided circumscribing cylindrical element l2, upstanding therefrom, and conductively attached thereto.

The ends of the cylindrical element 12 are enclosed by conductive surfaces [7, I8, conductively attached at their periphery to the cylindrical surface.

In the embodiment shown, the polarizations of the antennas are vertical. However, the directions of polarization of the antennas are immaterial to the operation of the invention.

The dimensions of the several elements of the invention depend principally on the maximum wavelength for which effective shielding is desired. In terms of maximum operating wavelength, the diameter of the cylinder may be of the order of four wavelengths and the length of the cylinder may be of the order of three wavelengths. The radial width of the vanes, I3 to It,

is approximately one-half wavelength. The spacing between adjacent vanes is of the order of, but greater than one-half wavelength. The optimum spacing preferably is determined experi mentally and is not necessarily uniform.

In an experimental model, wherein the antennas were circularly polarized, the addition of the vanes, I3 to IE, to the cylindrical element 12 produced additional shielding between antennas i0 and H sufficient to reduce the amount of energy fed from one antenna to the other by a factor of at least 100 to 1 over the frequency range of 1.4 to 1. More or fewer than four vanes may be used, according to the amount of shieldin required.

In view 01 the foregoing description, it will be apparent that the scope of the invention includes the combination of vanes substantially as described with structures of other than cylindrical shape. For example, prisms or other shapes may be circumscribed by vanes in accordance with the invention.

It will be understood that the embodiment of the invention herein described is exemplary only and that the scope of the invention is to be determined by the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purpose without the payment of any royalties thereon or therefor.

What is claimed is:

1. Shielding means for electromagnetic waves within a predetermined frequency band comprising a conductive cylindrical element and a plurality of spaced conductive annular vanes conductively attached perpendicular to and circumscribing the convex surface of the cylindrical element, the radial width of the vanes being substantially a half wavelength and the spacing between adjacent vanes being substantially equal to but greater than one-half wavelength at the lower end of said frequency band.

2. In combination, a pair of spaced antennas, a pair of extended shielding members positioned between the antennas, conductive means connecting the peripheries of the shielding members, and shielding vane means carried externally by the conductive means.

3. Shielding means for spatial insertion between adjacent sources of electromagnetic energy to provide electromagnetic shielding therebetween over a predetermined frequency band, said shielding means comprising an enclosed conductive chamber having a length of substantially three wavelengths, a plurality of parallel vanes attached to the periphery of said chamber and lying perpendicular to the longitudinal axis of said chamber, said vanes extending outward from said periphery for substantially a half wavelength,

the spacing between adjacent vanes being substantially equal to but greater than one-half wavelength, all of said dimensions in terms of wavelength being measured at the lower end of said frequency band.

4. Shielding means for spatial insertion between adjacent sources of electromagnetic energy to provide electromagnetic shielding therebetween over a predetermined frequency band, said shielding means comprising a closed conductive cylinder having a length of substantially three wavelengths and a diameter of substantially four wavelengths, a plurality of parallel vanes circumscribing said cylinder and perpendicular to the longitudinal axis of said cylinder, said vanes having a radial width of substantially one-half wavelength and a spacing between adjacent vanes substantially equal to but greater than one-half wavelength, all of said dimensions in terms of wavelength being measured at the lower end of said frequency band.

THURE E. HANLEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,996,422 Hurley Apr. 2, 1935 2,064,635 Stern Dec. 15, 1936 2,359,620 Carter Oct. 3, 1944 2,395,560 Llewellyn Feb. 26, 1946 2,411,976 Peterson Dec. 3, 1946 2,455,888 Brown Dec. '7, 1948 

